At least 30 people lost their lives on Wednesday when four bombs hit Shia pilgrims across Baghdad as they gathered to mark the anniversary of the death of Shiite imam Moussa al-Kadhim, a great-grandson of Prophet Muhammad, according to Al Jazeera.

In the southern city of Hillah, two bombs, including one detonated by a suicide car bomber,  killing 22 people and wounding 38. Two more car bombs killed four people in the mainly Shia city of Balad,  Al Arabiya reported.

Al-Qaeda’s Iraqi affiliate, Islamic State of Iraq, claimed responsibility for the attack on the religious office, according to AP. 

On Sunday at least six people were killed when two mortar bombs struck a Baghdad square packed with Shia Muslim pilgrims.

Earlier this month, 26 people were killed and more than 190 wounded when a bomb denotated by suicide bomber exploded outside a Shia religious office in the capital.

Violence in Iraq has decreased  since its peak in 2006-2007, but attacks persist, especially in Iraq’s capital, Baghdad.

Political tensions have been high in Iraq since the last US troops pulled out in December, with the country’s fragile government, divided among Sunni, Shia and ethnic Kurdish blocks.